1. Related Applications
The present invention is related to co-pending U.S. patent application entitled "Power Fault Protection in a Computer System Having Multiple Power Supplies", Ser. No. 08/239,748, assigned to the assignee of the present invention and filed concurrently herewith.
2. Field of the Invention
The present invention relates to power management for portable electronic systems. More particularly, the present invention relates to power fault detection and protection methods and mechanisms for portable computer systems having multiple power sources.
3. Art Background
As the computer revolution has progressed, computing machines have become ever smaller, yet more powerful. The advent of advanced semiconductor technologies has resulted in computers that are easily transportable. Today, portable laptop computers which utilize advanced packaging techniques are nearly as common as desktop computers were just a few years ago. The efforts of computer architects today, using emerging technologies, is the ever smaller, faster portable computer that is lightweight, extremely modular and flexible in its use.
An important consideration in designing portable computing devices, or any portable electronic device is the configuration of the power system. Ideally, when a computer is used at a fixed location, the user should be able to plug the device in to an AC-power outlet and derive power for the device by means of an AC adapter or equivalent technology, where DC power is supplied to the computer after being converted by the AC adapter. When the portability aspect of the device is being utilized, and electric wall sockets are unavailable, the portable computer must operate from battery power. While battery technologies are improving, they still suffer the unfortunate characteristics of being large and heavy relative to the overall size and weight of portable devices.
In an effort to meet the above goals of lightweight, modular systems having increased flexibility, computer makers have begun exploring the possibility of providing multiple power sources, including more than one battery compartment. This allows for more flexibility in designing around space constraints in tightly packaged small systems. The price of this increased flexibility is increased complexity with respect to power management subsystems. For example, when more than one battery pack is provided for, the computer system must provide additional battery contacts and provide for the coordination of selecting an optimal operating power source.
Another object of the evolving computer revolution has been to make computers more "friendly". Computers that lose data or require re-initializing because of power problems are decidedly unfriendly. Further, it is a disadvantage of many systems to have to shut down the computer system when changing from one power supply to another. It would be desirable, and is therefore an object of the present invention, to provide a reliable power supply management system for portable computers having multiple power sources.